The present invention relates to a semiconductor device and, particularly, relates to a semiconductor device having a feedback equalizer.
A feedback equalizer equalizing a waveform by using data which is preceding in time (in the past) is known. As feedback equalizers, for example, feedback equalizers of various configurations such as a decision feedback equalizer (hereinbelow, also called DFE) exist.
A DFE is provided for, for example, a SerDes (SERializer/DESelializer) circuit performing mutual conversion between serial data and parallel data and used to equalize the waveform of serial data.
The SerDes circuit is provided on the inside of a semiconductor device and is mounted on, for example, a card of PCI Express. PCI Express includes a plurality of standards of different transfer rates. In standard PCI Express 1.1 (hereinbelow, standard Gen1), the transfer rate is 2.5 Gbps. In standard PCI Express 2.0 (hereinbelow, standard Gen2), the transfer rate is 5 Gbps. In standard PCI Express 3.0 (hereinbelow, standard Gen3), the transfer rate is 8 Gbps. In standard PCI Express 4.0 (hereinbelow, standard Gen4), the transfer rate is 16 Gbps. The DFE in the SerDes circuit mounted on the PCI Express card is required to operate at a transfer rate adapted to the standard employed to the card.
The DFE is described in, for example, patent literature 1.